Some wireless communications techniques may use Orthogonal Frequency Division Multiple Access (OFDMA). One example may be found in the communications standard defined by the Institute of Electrical and Electronic Engineers standard 802.16 (IEEE 802.16). In this approach to wireless communications, data to be communicated over a channel may be fragmented into multiple segments of various lengths, and those segments distributed among multiple sub-channels operating at different frequencies, which are transmitted at the same time. When those multiple sub-channels are received, the received data may be reconstructed into the original data pattern. To better illustrate the arrangement of these transmissions, they are frequently represented in graphical form, with the sub-channels along one axis and time (usually represented by slots or symbols) along the other axis, forming a rectangular block that represents a sub-frame. Overall throughput of the channel may depend on how fully the sub-frames are packed with data. If a sub-frame to be transmitted has a pre-determined size (e.g., pre-determined number of sub-channels and pre-determined number of slots) and the data can be fragmented at any point, then the data may be fragmented specifically to fit exactly into that predetermined size, resulting in complete usage of the sub-frame. However, if the data may only be fragmented along specific boundaries, the fragments may not fit exactly into the available sub-frame, resulting in wastage (i.e., least one part of the sub-frame doesn't contain any useful data during at least one portion of the transmission).